Thanks for the replies everybody. I really appreciate the explanations and encouragement. I have obtained a new bull gear and cross-slide crank, I'll be tearing it down all the way and I'll start a new thread to document the restoration. I agree that will be the best way to learn about its' workings.
I actually obtained another lathe recently, a 10D (I think) in really nice shape with a milling attachment and a whole bunch of accessories for $300, so I had no choice but to drag that home as well. I'm not sure if I'll be keeping one or both, I guess space will be the determining factor. I'll post some pics of the new one and the restoration of the 6 inch when I get home in a week or so.